1. Technical Field
This invention generally relates to a grinder, and more specifically relates to a compact grinder.
2. Background Art
Hand held grinders are common tools that are used for a variety of applications. Typically a grinder includes a motor that drives a wheel (such as a grinding wheel, wire brush, or cutting disc). Many grinders include a drive shaft from the motor and a gear system coupled to the drive shaft that changes the direction of rotation. Often the direction of rotation is changed by 90xc2x0. Also, many grinders include a lock pin that can be pressed inwardly to lock the drive shaft relative to the housing of the grinder so that a clamping screw can be loosened or tightened to mount the wheel on the grinder or remove the wheel from the grinder.
Hand held grinders are useful because they are portable and thus the grinders can be taken to the part to be worked, rather than the part having to be moved to a stationary grinder. They are often useful in working surfaces of large or bulky machines or parts. As such, they are often used in automobile repair, metal fabrication, welding shops, heavy equipment repair, and woodworking. However, past hand held grinders have not been able to reach many surfaces or they have required excessive work or modification to reach many surfaces.
Therefore, there existed a need to provide a hand held grinder that is compact and that is able to work hard-to-reach surfaces such as inside corners. The present invention recognizes this need, which has not heretofore been recognized and addressed.
According to the present invention, a hand-held grinder includes a motor and a mounting surface coupled to the motor. A housing supports the mounting surface and the motor. A grinding wheel abuts and is secured to the mounting surface, and the grinding wheel extends beyond an end of the housing. A line that is tangential with the grinding wheel distal from the housing, and that is tangential with the end of the housing, may be at an angle of less than about 45xc2x0 relative to a plane of rotation of the grinding wheel.
The grinder may also include a drive shaft coupled to the motor, a driving gear coupled to the drive shaft, and a driven gear engaging the driving gear and fixed to the mounting surface. The driven gear and the mounting surface may be part of a unitary member. Such a unitary construction allows the grinder to be more compact.
The housing may define a bottom housing surface that is substantially coplanar with the mounting surface. This substantially coplanar construction allows the grinder to be constructed so that only a very small gap separates the grinding wheel from the housing, thereby producing a more compact grinder. The housing may also define a top housing surface opposite from the bottom housing surface and an angled housing surface between the bottom housing surface and the top housing surface that forms an acute angle with the bottom housing surface, thereby forming a tapered end of the housing. The tapered end further adds to the compact design of the grinder and particularly aids in allowing the grinder to reach tight spaces such as inside corners.
Also, the grinder may include a telescoping feature wherein the housing includes a first member and a second member. The first member is moveable relative to the second member to change a length of the grinder. The telescoping feature is desirable because some hard-to-reach surfaces require a longer tool while others require a shorter tool. The telescoping feature allows a single grinder to access both types of surfaces.
The grinder may include a lock pin supported by the housing that is aligned with, but generally biased away from, a radial hole in the drive shaft. The lock pin may be selectively forced into engagement with the radial hole, thereby preventing rotation of the drive shaft relative to the housing. The lock pin locks the rotating parts of the grinder relative to the housing so that a clamping screw can be tightened or loosened to secure or remove a wheel from the grinder. Without the lock pin, a user would have to directly access the mounting surface or other moving parts of the grinderxe2x80x94this would likely require extending such parts beyond the grinder housing to make them accessible.
The foregoing and other features and advantages of the invention will be apparent from the following more particular description of preferred embodiments of the invention, as illustrated in the accompanying drawings.